African sleeping sickness in humans is a potentially deadly disease caused by trypanosomes (Trypanosoma brucei spp.). Central to inhibiting the spread of this rapidly re-emerging disease is control of the arthropod vector, the tsetse fly (genus Glossina). Tsetse harbors a commensal endosymbiotic microorganism (Sodalis glossinidius) that lives in the midgut in close proximity to the trypanosomes. The goal of this research is to exploit this symbiotic flora for the purpose of decreasing tsetse's capacity to transmit trypanosomes. To accomplish this goal, I plan to improve upon an existing extra-chromosomal plasmid-based transformation procedure by using homologous recombination to incorporate 'effector molecule' genes into Sodalis' chromosome. 2 candidate molecules, with demonstrated trypanolytic activity, are available for this purpose: tsetse attacin and vertebrate BMAP-27. Recombinant Sodalis will be reintroduced to tsetse. These 'paratransgenic' flies and their offspring will then be monitored for changes in fitness, stability of recombinant protein expression and trypanosome vectorial capacity.